Integral thrust neutralizer for rocket engines

ABSTRACT

Thrust-neutralizing means for a missile having a rocket motor having igniter means, said neutralizing means compressing a set of blowout ports in the casing of said igniter and blowout discs in said ports, a similarly spaced set of ports in the neck of the combustion chamber of the rocket motor, and a similarly spaced set of ports in the body of the means which couples the motor to the missile. The igniter means is rotatable so that all sets of ports can be aligned in the &#39;&#39;&#39;&#39;safe&#39;&#39;&#39;&#39; position. The ports in the body of the coupling means is forwardly angled so that any gas discharge thru these ports provides backward thrust for the missile.

United States Patent [191 Katcher Jan. 15, 1974 INTEGRAL THRUST NEUTRALIZER FOR ROCKET ENGINES [75] Inventor: Emanuel E. Katcher, Washington,

221 Filed: Jan. 10, 1973 21 Appl. No.: 322,348

[52] US. Cl 60/229, 60/256, 60/39.09 R,

60/39.82 E, l02/49.7 [51] Int. Cl. F02k 9/04 [58] Field of Search 60/229, 234, 253-256,

60/39.82 E, 39.09 R, 39.1, 39.47, 223; 102/496, 49.7, 70 R; 89/].812

[56] References Cited UNITED STATES PATENTS 3,529,418 9/1970 Puckett et 211 60/256 X 3,423,931 1/1969 Schwarz et a1 60/39.47

Primary Examiner-Carlton R. Croyle Assistant Examiner-Robert E. Garrett Attorney-R. Si Sciascia [57] ABSTRACT Thrust-neutralizing means for a missile having a rocket 'motor having igniter means, said neutralizing means compressing a set of blowout ports in the casing of said igniter and blowout discs in said ports, a similarly spaced set of ports in the neck of the combustion chamber of the rocket motor, and a similarly spaced set of ports in the body of the means which couples the motor to the missile. The igniter means is rotatable so that all sets of ports can be aligned in the safe position. The ports in the body of the coupling means is forwardly angled so that any gas discharge thru these ports provides backward thrust for the missile.

6 Claims, 2 Drawing Figures INTEGRAL TIIRUST NEUTRALIZER FOR ROCKET ENGINES STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalities thereon or therefor.

BACKGROUND OF THE INVENTION This invention relates to means for neutralizing the thrust of a gas-propelled missile and especially to such neutralization for safety purposes when the missile is being stored or shipped.

A danger exists in missiles having rocket propulsion units that the igniter or propellant will be accidentally ignited and cause the missile to be propelled, thereby causing damage. Such accidental ignition can be caused by electrostatic energy, electromagnetic energy, stray voltages, lightning transients, personnel errors, inadequate circuit design, faulty electrical components, fire or heat, etc.

It is therefore desirable that the forward thrust of the gases expelled from the nozzle in the rear of the missile be neutralized either completely or to the extent that not enough thrust remains to propel the weight of the rocket forward.

Present methods of obtaining thrust neutralization include:

1. Shipping and storing the rocket without an igniter. This means that personnel have to be ever vigilant to see that no errors occur.

2. Providing a thrust neutralizer attachment that is externally placed on the rocket nozzle and must be removed for firing. These designs are usually bulky and heavy, causing personnel to try to avoid their use.

3. Providing blowout discs at both igniter and nozzle locations. Full thrust is obtained by installing a solid metal part into the igniter location prior to operational use, a time'consuming job.

SUMMARY OF THE INVENTION The objects and advantages of the invention are accomplished by providing the internal igniter casing and the missile casing with matching ports, the missile ports being angled forward so that gas issuing from the missile ports gives a backward thrust to the missile, thereby tending to neutralize the forward thrust provided by nozzle gases. The igniter can be rotated so that its ports are in alignment with the missile ports for safety. The igniter ports are closed with blowout discs which are ejected when the igniter is ignited, thereby allowing the internal gases to escape thru the ports.

An object of the invention is to neutralize or lessen the thrust provided by the nozzle gases of a rocket missile.

Another object is to neutralize or lessen by internal means the thrust provided by the nozzle gases of a rocket missile.

OBJECT CLAUSE Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal cross-section of the aft end of a rocket missile in accordance with the present invention.

FIG. 2 is a side view of the igniter used with this invention.

DETAILED DESCRIPTION FIG. 1 shows schematically the rear end of a rocket missile. Welded to the tubular coupling section 10 of the rocket motor is a rather bottle-shaped combustion chamber 12 with a nozzle 14 attached at its rear. A hollow tube of propellant charge 16 fits inside the wall of the combustion chamber 12. At the forward end, the combustion chamber 12 is narrowed into a neck in which a cylindrical igniter unit 18 is placed.

FIG. 2 provides a more detailed partly sectional view of the igniter section of the rocket motor. The igniter 18 is a unit with a cylindrical casing inside of which explosive squibs and igniter main charge are placed which are fired by an electrical signal. The signal is brought in by a pair of wires 20. The igniter has a scored blowout disc 22 in its side which is adjacent to the combustion chamber 12. Igniting the sq uibs generates hot gases which blow out the igniter rear disc 22 and ignite the propellant charge 16. A look ring 24 is placed in front of the igniter 18.

A plurality of gas-discharge ports 26 are spaced around the body of the coupling section 10 and a light access strap 28 is tightened around the ports 26. The gas-discharge ports 26 are angled in the forward direction so that any gas discharging from the ports 26 will discharge in the forward direction.

The neck of the combustion chamber 12 also is formed with a plurality of gas-discharge ports 31. This set of ports is spaced the same as the igniter blowout ports 30 so that the latter can be aligned with the combustion-chamber ports 31.

The igniter casing has a plurality of holes or blowout ports 30 drilled thru it, the number being equal to the number of gas discharge, or body blowout, ports 26. In each igniter blowout port 30 is placed a plug comprising a scored metallic disc 32. All blowout discs may be manufactured from a metal such as copper, for example.

The igniter casing is grooved 41 and 45 to contain two O-rings 43 and 47 which seal the space between the casing and the neck of the combustion chamber so that no gas may discharge forwardly or backwardly thru the neck but must go thru the: gas-discharge ports after the blowout discs fail. If the pressure builds up sufiiciently so that it cannot be relieved thru the gas discharge ports, the rear blowout disc 22 fails and some gas is discharged into the hollow portion of the combustion chamber.

The igniter 18 is rotatable by means of a central shaft 34, the end of which is coupled to a radial shaft 38 by means of gearing 36. The radial shaft 38 extends outside the motor body l0 to a female key fitting 40. The key fitting 40 can be turned, thereby rotating the igniter casing, by means of a turn key 42.

To place the igniter in its safe position, the igniter is rotated so that its blowout ports 30 are aligned with the body gas discharge ports 26 and the combustion cham ber ports 31. The operator who is wielding the turn key 42 can observe the aligning of the ports by lifting the access strap 28 from one of the ports 26 and looking thru the port. Then, if the igniter squibs ignite by accident, the gas which is generated blows out the blowout discs 32 and goes thru the igniter blowout ports 3% and the body gas discharge ports 26. Since the gas is propelled at a forward angle to the body of the missile, a thrust having a backward force component is generated. This backward force component acts to diminish the forward thrust of the gases which exit to the rear of the rocket motor thru the end of the nozzle l4.

When it is desired to arm the missile, the igniter is rotated so that its blowout ports 3'1 do not align with the body blowout ports 26. When ignited, the igniter gases cannot blow out the igniter blowout discs 32 but can and do blow out the rear igniter blowout disc 22, allowing the hot igniter gases to ignite the propellant charge 16.

A sectional view of the igniter i8 is shown in FIG. 3. This shows the blowout discs and their locations in slightly greater detail.

A futher safety feature is provided by a safety pin 4% which can be fitted into a bore in the female key fitting 40 to lock the shaft 38 and therefore the igniter 18 in the safe position, thus positively preventing igniter rotation.

GENERAL CLAUSE Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. Thrust-neutralizing means for a rearwarddischarging rocket motor which is used to propel a missile comprising, in combination:

combustion chamber means having a neck formed with spaced ports around the periphery of said neck;

coupling means attached to the front of said combustion chamber means for attaching said rocket motor to the main body of said missile,

said coupling means being formed with a plurality of gas-discharge ports spaced around its periphery, said ports being angled so that gas discharging thru said ports travels toward the front end of the rocket motor thereby imparting a rearward thrust to the missile;

igniter means located inside the neck of said combustion-chamber means and having a casing formed with a plurality of blowout ports which are equal to the number of said gas-discharge ports and to the number of said combustion-chamber ports and which are correspondingly spaced with said latter two sets of ports,

said igniter means having a plurality of blowout discs,

each being placed in a different blowout port so as to seal the port,

said igniter means also having a central shaft whereby the igniter means may be rotated into alignment with said combustion-chamber ports and said gasdischarge ports; and

means for rotating said igniter means from the outside of said coupling means.

2. Thrust-neutralizing means as in claim 1, said combustion-chamber neck and said igniter casing being cylindrical in shape and coaxial with each other.

3. Thrust-neutralizing means as in claim 1, wherein said igniter means includes gas-sealing means for preventing the discharge of gas forwardly thru the neck of said combustion-chamber means.

4. Thrust-neutralizing means as in claim 1, wherein said igniter means includes gas-sealing means for preventing the discharge of gas rearwardly thru said combustion-chamber means.

5. Thrust-neutralizing means as in claim ll, wherein said means for rotating said igniter means shaft means connected to said igniter means and key means for turning said shaft means.

6. Thrust-neutralizing means as in claim 5, further including locking means for locking said shaft means in a predetermined position. 

1. Thrust-neutralizing means for a rearward-discharging rocket motor which is used to propel a missile comprising, in combination: combustion chamber means having a neck formed with spaced ports around the periphery of said neck; coupling means attached to the front of said combustion chamber means for attaching said rocket motor to the main body of said missile, said coupling means being formed with a plurality of gasdischarge ports spaced around its periphery, said ports being angled so that gas discharging thru said ports travels toward the front end of the rocket motor thereby imparting a rearward thrust to the missile; igniter means located inside the neck of said combustion-chamber means and having a casing formed with a plurality of blowout ports which are equal to the number of said gas-discharge ports and to the number of said combustion-chamber ports and which are correspondingly spaced with said latter two sets of ports, said igniter means having a plurality of blowout discs, each being placed in a different blowout port so as to seal the port, said igniter means also having a central shaft whereby the igniter means may be rotated into alignment with said combustion-chamber ports and said gas-discharge ports; and means for rotating said igniter means from the outside of said coupling means.
 2. Thrust-neutralizing means as in claim 1, said combustion-chamber neck and said igniter casing being cylindrical in shape and coaxial with each other.
 3. Thrust-neutralizing means as in claim 1, wherein said igniter means includes gas-sealing means for preventing the discharge of gas forwardly thru the neck of said combustion-chamber means.
 4. Thrust-neutralizing means as in claim 1, wherein said igniter means includes gas-sealing means for preventing the discharge of gas rearwardly thru said combustion-chamber means.
 5. Thrust-neutralizing means as in claim 1, wherein said means for rotating said igniter means shaft means connected to said igniter means and key means for turning said shaft means.
 6. Thrust-neutralizing means as in claim 5, further including locking means for locking said shaft means in a predetermined position. 